In your 2oz difference example, you're comparing a Nunatak arc to a Nunatak sleeping bag. A quick look shows they're pretty much the same, except that the bag gives a hood and a way to zip it closed. Nunatak is the rare company that offers the same bag in a quilt. For a more apples to apples, you need to take a top of the line quilt, such as the Nunatak Arc Alpinist and compare it to a top of the line sleeping bag.

Compared to the Western Mountaineering Ultralite 20*, both are 20* insulation, both have 2.5" of loft per layer, based on their fill weights, they appear to be the same grade of down fill power. However, since the WM has to fill underneath you, it takes more weight, and the comparable WM bag comes in 9oz heavier.

This is somewhat situational, but using a quilt in a hammock--especially a netted hammock--is a lot easier than using a fully-zipped mummy bag.

Sure, you could just zip a portion of the bag up to make a foot box, but why pay the weight penalty for the rest of the stuff you're not using on it? If you're not going to get a benefit out of the insulation compressed underneath you (which is a greater area in a hammock than sleeping on a 20" wide pad), and it's a pain to struggle with zipping the thing up the whole way, then why have the extra weight?

That's not to say that sleeping bags don't have a place--and a valid one--among folks wanting to spend time outdoors. I just find that it's easier, and lighter, to use a quilt when hammocking.

were talking about the same quilt vs the same bag with the same rating with the same fabric and the same insulation by the same company ... 2 oz difference

thats apples to apples if there ever was one

as to sleeping systems ... you can easily use yr other clothing under a bag same as a quilt ... now some may say that you need a wider bag (i dont personally) .... but as witnessed by those "narrow vs wide" quilt threads, youll likely need a wider quilt for the same use anyways .. some may say "well it doesnt fit my very large puffy" (something like a mex reflex), i would say are you using a quilt at temps where you need that kind of jacket, ie below 0F ???

people choose to use what ever they want ... just dont be one of those "only quilts are UL" or vice versa people

like i said if i need one single do it all bag for any sport (climbing, backpaking, at the cabin, ledge bivies, snow caves, etc ...) in as many conditions as possible id get a 20F bag ....

Yeah, Eric's spot on here. For once. That's as apples to apples as a comparison gets. I get the sleep system concept, but the simple fact is, a mummy bag can do everything a quilt can, and then some by adding draft protection depending on the climate. If you're one of those people who need more space to thrash, feel claustrophobic, I totally get not buying a mummy bag. But quilts are presented here as the fix for all possible sleeping situations and that's simply not the case. The quilt kool aid gang around here is pretty intense, but there's room for both, especially given that mummy bags have dramatically come down in weight.

I think the difference between those that use quilts and those that don't is that those that use quilts have used mummy bags and found a superior option. For those who have not used a quilt then their perspective becomes moot.

Not to mention it is easier to drink koolaid under a quilt than under a mummy.

don't have quite experience, but just to clarify, you can get mummy bags with no zip, is lighter and you never end up with your bag's zip digging in you, if you turn you do end up with the hood warmer not where you wanted it but that's all. I tried mummy zipless and I found that no problem relative to only having mummy zipped previously. I think a full zip is about 150g?

6' of #5 zipper tape and 1 #5 locking slider weigh 1.5oz so your talking very little weight difference between a quilt and a sleeping bag with the same amount of fabric and fill. The only real way to shed weight in a quilt would be to reduce the shoulder, hip and foot circumference but this is rarely the case.

>>were talking about the same quilt vs the same bag with the same rating with the same fabric and the same insulation by the same company ... 2 oz difference<<

If you're only in the market for a Nunatak, then the comparison is valid. However, if you don't trust Nunatak's sleeping bag design (as I don't), then the comparison of quilts to sleeping bags falls apart. Two reasons I don't trust Nunatak's bag design: I've heard lots of warmth complaints related to top-zip bags like GoLite's due to the lack of insulation from the zipper area, and if you need to cool off your options are more limited (e.g. not as easy to stick a leg out).

Anyone ever heard a gear review for a Nunatak bag? I'm very skeptical that it performs as well as the equivalent quilt. Unless it has equal performance, it's not a valid comparison.